The goals of this project are to use human lung tissue to study the development of preneoplastic (and possibly neoplastic) lesions induced by chemical carcinogens, and to study the ability of selected agents to modify the effects of chemical carcinogens on human lung tissue. Human bronchial epithelial tissues are to be exposed in vitro to chemical carcinogens, as well as to anti-carcinogens. These human bronchial tissues are then to be transplanted and maintained in vivo in the hamster and in the athymic nude mouse as xenografts.